FIG. 1 is a perspective view of a conventional printed circuit board (PCB). Referring to FIG. 1, on a PCB substrate 100, two surface-mount (SMT) DC block (or ac-coupling) capacitors 101 are respectively mounted to two soldering pads 104 connected with a pair of high-speed serial transmission lines 102, which are configured to interface two high-speed logic integrated circuits (IC). Examples of logic IC interface configurations are LVDS (low-voltage differential signaling) and CML (current mode logic). Meanwhile, because of the limited size of the PCB 100, plated through-hole (PTH) vias 103 are needed to connect signals in the top layer to the bottom (or vice versa). The presence of both DC block capacitors 101 and PTH vias 103 in the high-speed transmission lines 102 and 105 introduces discontinuities to high-speed electrical signals running on the PCB traces, which often changes the characteristic impedance along the traces and causes a considerable amount of signal reflections. Thereby, the signal quality in the transmission lines is degraded.